Process of manufacturing dialkyl-barbituric acids.



UNITED STATES PATENT OFFICE.

timer, STEPHAN AND PAUL HUN'SALZ, or BERLIN, GERMANY, ASSIGNORSTocHEMIscnE I FABRIK AUF AOTIEN (VORM. sc ERING), OF BERLIN, GERMANY.

PaocEss-oF MANUFACTURING DIALKYL-BARBITURIC news. 1

specification of 'Lettere Patent. I

Patented Feb. 18, 1908.

Application filed February 16. 1905. Serial No. 246.835.

sia, German Empire, have invented a new and useful Improvement inProcesses of Manufacturing DialkyleBarbituric Acids, of

which the-following is a specification.

.According to our invention. dialkyl-b'arbituric acids, which aretknownas valuable soporifics, and

which have 'the general for- '(in this formula R.is meant for an alkyljgroup), are manufactured by causing acids to react upon thecorresponding dialkylmalonyl-guanidins, answering the general.

formula this process.

- monoalky derivatives, can be obtained by Ewamp les:

rates out.

whereby the diethyl barbituric acid sepa By recrystallizing from waterthe said acid is further urified.

2. 5 kilograms o diethyl-malonyluani-' din are heated with 25 kilogramso 10% sulfuric acid for two hours in a rd'flux condenser.

On cooling the diethyl barbituric acid crystallizes out and is thenfurther 3. Onekilogram of diethyl-malonyl-guanidin is heated with 12kilograms of hydrobromic acid for several hours "in a closed tube. Aftercooling the product of reactionseparates out.

4. One kilogram of dimethyl-malonylguanidin is heated with 10 kilogramsof fuming hydrochloric acid to about' 120 centigr-ade for 4 'to 5 hours.Then one proceeds as indicated in the first example.

We claim as our invention The herein described method of producingdialkyl barbituric acids, having the herein mentioned general formula,which consists in causing an acid to react in the presence of water uponthe corresponding dialkylmalonyl-guanidins, thereby introducing oxygenin place of the imino group by hydrolysis, and thenseparating theresulting dialkylbarbituric acids.

In testimony whereof we have here unto set our names in the presence oftwo subscribing witnesses.

KARL STEPHAN. PAUL HUNSALZ. Witnesses:

HENRY HASPER, WOLDEMAR HAUPT.

